Hydraulic transmission



Sept. 21, 1943. F. KUGEL HYDRAULIC TRANSMISSION Filed April 25,-1939 5Sheets-Sheet l Caz ' INVENTOR FRH Z KUCJEL ATTORNEYS uma'dm HYDRAULICTRANSMI S S ION Filed April 25, 1959 3 Sheets-Sheet 2 3 Cam V '7 \& a

INVENTOR BY FmTz KuuE ATTORN EYS Se t. 21, 1943. F. KUGEL HYDRALILICTRANSMISSION Filed A ril'zs. 1939 3 Sheets-Sheet 3 L J- INVENTOR FRITZKUGEL,

W ATTORNEYS Patented Sept. 21, 1943 2,329,915 HYDRAULIC TRANSMISSIONFritz Kugel, Heidenheim, Brenz, Germany, as-

signor to American Voith Contact Co. Inc., New York, N. Y., acorporation of New York Application April 25, 1939, Serial No. 269,873In Germany April 26, 1938 10 Claims.

This invention relates to hydraulic machinery, and in vparticular, tohydraulic power transmitters, such as hydraulic couplings or torqueconverters.

One object of this invention is to providea hydraulic torque converterhaving either its primary or secondary rotor or both of them constructedas a plurality of blade assemblies connected to a common shaft, butspaced apart from each other so that the different blade assemblies aresubjected by the working fluid to difierent forces, the vaneconfiguration or profile being varied between the assemblies to providethe most suitable form for theoperating conditions in the channelsbetween the blades in the particular blade assembly.

Another object is to provide a hydraulic power transmitter, wherein theblades of at least one of the rotors are divided up into at least twoassemblies, spaced apart from each other and having blade constructionsor cross sections which differ considerably between the two or moreblade assemblies so that the blade cross section for each assembly canbe made most favorable for the particular fluid conditions which thatblade assembly encounters.

Another object is to provide a hydraulic power transmitter, such as atorque converter, with primary and secondary rotors, one of these rotorshaving a plurality of blade assemblies, at least one of these bladeassemblies in the multistage rotor being constructed and arranged as apump rotor, whereas at least one of the other blade assemblies connectedto the same rotor is constructed and arranged as a turbine rotor.

Another object of this invention is to provide a hydraulic powertransmitter, such as a torque converter, with primary and secondaryrotors, each of these rotors having a plurality of blade assemblies, atleast one blade assembly of each of the multistage rotors beingconstructed and arranged as a pump rotor, and at least one bladeassembly connected to the same rotor being constructed and arranged as aturbine rotor.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

Figure 1 is a cross section through a blade of a blade assemblypertaining to a torque converter according to the invention andgraphically illustrates the velocities and the way of movement of aliquid particle.

Figure 2 shows, on anenlarged scale, the velocity triangles of Figure 1.

Figure 3 diagrammatically illustrates a longitudinal section through atorque converter according to a first embodiment of the invention.

Figures 4, 5, 6 and '7 respectively show the entrance and exitvelocities for the various blade assemblies of Figure 3.

Figure 8 is a diagrammatic illustration of a second embodiment of theinvention. 1

Figures 9, 10, 11 and 12 respectively show the entrance and exitvelocities of the variousblade assemblies of Figure 8.

Figure 13 is a third embodiment of the invention, and

Figures 14, 15,16, 17 and i8 illustrate the various velocities of theblade assemblies pertaining to Figure 13.

' General arrangement In general, the hydraulic power transmitter of thepresent invention consists of a casing con taining primary and secondaryrotors, one of the rotors having it blades distributed among a pluralityof blade assemblies. These blade assemblies are separated or spaced fromeach other along the orbital path followed by the working fluid. As thevelocity and pressure conditions of the working fluid vary in the pathfollowed thereby, it is thus possible to adapt for each blade assemblyablade conflguratiomcross section or profile which is most eflicientlyformed and therefore most favorable in its operation for the particularcondition of the working fluid at that point in the circuit. Inparticular, the em bodiment chosen for purposes of illustrationshows atorque converter with a primary rotor having a single stage, namely, asingle blade assembly having a pump action. In contrast, however, thesecondary rotor consists of a plurality of blade assemblies having aturbine action.

Hithereto, in order to obtain a good'working efiiciency. in hydraulictorque converters, it has been found that as great as possible anacceleration of the relative flow of the workingfluid should occurwithin the blade channels during operation because a retardation of theflow inside a blade channel causes a transformation of kinetic energyinto potential energy, which is invariably accompanied by great lossesin efficiency. To obtain the said acceleration of the relative flow ofthe working fluid, the blades have to be given a certain definite shape.Furthermore, provision must be made for securing a satisfactoryadmission of the working fluid to the inlet edges of the bladeassemblies under widely varying operating conditions, such as areusually met with in torque-converters; to meet this last mentionedrequirement, the inlet edges of the vanes are given a substantialthickness and are shaped on the lines of the Gottingen wing section,whereas the exit portions of the blades must be as sharply tapered aspossible. v

This construction, however; produces greatly diverging blade channels,particularly if the entrance and exit angles at which the fluid entersand leaves the blade assemblies differ only slightly so from each other.These angles are dependent,

aside from other factors, upon the pressure head to be converted in theparticular blade assembly. The greater this pressure head the more theentrance and exit angles must differ from one another, and hence, themore closely will the blade approach the ideal theoretical bladeprofile.

With torque converters, particularly when used in connection withvehicles, it is desirable when starting the vehicle to allot only asmall total pressure head to the rotors in order to obtain a powerfultorque conversion. However, when using torque converters withmulti-stage rotors, this way of operation has the disadvantage that onlya small pressure head can be utilized in each stage according to theparticular operating conditions, since the total pressure head upon theindividual stages is divided up into positive portions so that the sumof the pressure heads to be employed in the individual stages of theparticular rotor is equal to the desired total pressure head employed.

Therefore, with multi-stage torque converters, various conditionsprevail which make the construction of blades of the most favorable formrather diflicult. On one hand, the greater number of blade assembliesleaves less space for the adequate and proper construction and shape-oithe blade surfaces, and, on the other hand, the pressure head to beconverted in each individual stage is in general lower than isdesirable. As mentioned above, it is much easier to obtain the bestpossible blade form when a large pressure head is to be employed ratherthan when only a small pressure head is obtainable, keeping in mind thatit i desired to speed up the flow of fluid within the blade channels, orat least to prevent a decrease in the velocity of the fluid which wouldreduce the efiiciency of the torque converter.

The above-mentioned drawbacks have been .overcome according to thepresent invention by providing a fluid power transmitter with at leastone multistage rotor, wherein one or more stages are constructed aspressure head-generating rotors or pump rotors (or impeller vane rings),whereas one or more stages are constructed as pressure head-consumingrotors, such as turbine rotors. By this construction a great freedom ofchoice is provided in selecting the value of the pressure which is mostefliciently suited to the particular blade form at that point in thecircuit.

With torque converters having single stage rotors, in fixing theparticular pressure head to be utilized in the circuit as well as themagnitudes of the other operating factors the blade form of theindividual rotor is more or less positively determined. In previoustorque converters with multi-stage blade assemblies, the distribution ofthe different pressure heads among the individual assemblies is broughtabout in such a manner that all blade assemblies of a given rotoroperate in the same manner. In other words, all of the blade assembliesof the primary side of the torque converter work always as pumps,whereas all of the blade assemblies of the secondary side work always asturbines.

In contrast to this prior development in a torque converter, accordingto the present invention the individual bladeassemblies of a given rotordo not all work in the same manner but in different ways. In otherwords, the primary rotor, as regards its individual stages, does notconsist solely of pressure head-generating blade assemblies, that is tosay, pump blade assemblies, but the primary rotor also contains one ormore pressure head-consuming blade assemblies, namely, blade assembliesoperating in the manner ,of turbines.

The pressure head H to be converted by one blade assembly can beexpressed by the following equation:

where H=pressure head.

ur=circumferential speed at the entrance of vanes (see Figure 1).

ue=circumierential speed atthe exit of vanes.

cui=projection of the absolute entrance speed or (see Figure 1) upon thecircumferential speed to (see Figure 2).

cua=projection of the absolute exit speed c: upon the circumferentialspeed us. g=acceleration due to gravity.

spond to turbine action.

From Figures 1 and 2, it will be clear that cos fl1='' T wherein 181 isthe entrance angle of the vanes, and Cmr is the relative velocity at theentrance of the vanes, i. e., the velocity or a fluid particle relativeto the respective vane; or

wherein W is the angular velocity of the wheel or rotor in radians persecond; r=radius of the entrance edge or the vanes; rz=radius of theexit edge of the vanes, the equation U Cu U C'u may be written asfollows:

gH= W r- Wr Cm cos B Whf- WnCm cos it Since furthermore wherein j1=crosssectional area of fluid passage at the entrance of the vanes, andfz=cross sectional area. at the exitof the vanes.

,Tg7g=g (1'z -13) cos )52 cos 3 It :is evident from this equationthatthe sign of the pressure head H is dependent upon various values. Afterthe entrance and exit radii 1'1 and n ofthe vanes have been determinedin accordance with the. particular requirements or the respective case,the pressure is substantially dependent on the entrance and exit angles51 and 52. With the aid of the above equations, the

designer will be in a position to provide the primaryor the secondaryshaft, or both shafts of a fluid transmission with pump blade assembliesas well as with turbine assemblies according to the invention.

Construction Referring now to the structural arrangements in detail,Figure 3 shows one embodiment of the invention as consisting of a torqueconverter having a primary shaft W1 and a secondary shaft W2. Connectedto the primary shaft W1 is aprimary rotor P having a singlebladeassembly-P1 with a primary core ring P2. Connected to the secondaryshaft W2 is a secondary rotor S provided with two stages or bladeassemblies S1 and S3, spaced apart from each other and mounted upon thesecondary core ring S3. The torque'converter is also provided with acasing C, consisting of casing halves C1 and C2, rotatably mounted bymeans of anti-friction bearings B1 and B2 upon the primary and secondaryshafts W1 and W2. The casing C is provided at its periphery with a brakesurface D, adapted to be engaged by a brake E, whereby the rotation ofthe casing C may be retarded. Connected to the casing half 02 is a guideblade assembly L, which may be made to occupy a stationary position bythe application of the brake E to the brak surface D.

The form or profile of the blades in Figure 3 as well as the velocitytriangles therefor are illustrated in Figures 4, 5, 6 and '7. Morespecifically, the blade assembly P1, or l-2 in Figure 3, which is a pumpblade assembly, has the blade profile shown in Figure 4 between thelines I and 2. In addition thereto, Figure 4 shows the vector orvelocity diagrams for the fluid particles at the entrance and exit ofthe vanes shown in Figure 4.

Thus, U1 and U2 respectively illustrate the circumferential speed orvelocities at the entrance and exit of these vanes, while C1111 and Canrep- -resent the relative velocities and C1 and C2 represent theabsolute velocities at the entrance and exit of these vanes.

Similarly, the blade assembly S1, or 3-4 in Figure 3, which is a turbineblade assembly, has the blade profile shown in Figure 5 between thelines 3 and 4. Figure 5 also shows the vector or velocity diagramspertaining to these vanes.

The guide blade assembly L, or 5-6 of Figure 3, which, as mentionedabove, may be held stationary by applying the brake E to the brakesurface D, has its profile illustrated in Figure 6 between the lines 5and 6. With the assumption that the guide blade assembly is heldstationary,

only absolute velocities occur at the entrance and exit of the guideblade assembly, and these velocities'are designated in Figure 6 as C5and Cs respectively.

The blade assembly S2, or 1-8 of Figure 3, which is a pump bladeassembly, has its profile illustrated between the lines I and 8 inFigure 7.

Figure 7 also illustrates the velocity diagrams pertaining to the bladeassembly 1-8.

From theabove it will be clear that by providing one and the same rotorwith a positive pressure head converting blade assembly and with anegative pressure head converting blade assembly, the form of the bladeassembly can be designed with the most favorable profile for the workingconditions of the fluid as they exist at that particular point in theorbital path of the fluid withinthe torque converter.

By forming one of the stages of the secondary rotor, such as the bladeassembly S2, as a pump blade assembly, which is, in effect,- driven bythe turbine blade assembly Si, the speed and, therefore, the force ofthe fluid'will be additionally increased beyond that imparted by theprimary or pump'blade assembly P1.

With reference to the design of the blade forms of the torque convertershown in Figure 3, the blade assemblies are so selected that, if thesecondary side of the converter has to operate with a total pressure ofthe value a, whereas for obtaining a favorable blade form, a pressure ofthe value b is necessary, this value b being absolutely greater than thevaluea, the first stage S1 may be allotted a pressure of the value aplus b, and the second stage can be allotted the pressure of the value-b. By this means a favorable blade form can be achieved for bothstages. In practice, however it may also be sufiicient if the pressurehead for the first stage S1 is chosen only slightly higher than thedesired value a for achieving a favorable blade construction as regardsacceleration in the blade channels because the second stage S2 can belocated at a position in the working circuit which is favorable for thedevelopment of the vane profile; so that for this stage also a favorablevane shape (that is one providing acceleration in the vane passages) canbe obtained with only a low head.

Operation In the operation of the hydraulic power transmitter of theinvention, such as the torque converter shown in Figure 3, the primaryshaft W1 tion of the blade assembly P1 of the primary rotor P, the oilis caused to circulate in an orbital path and successively engages thesecondary blade assembly S1, the guide blade assembly or guide wheel Land the secondary blade assembly S2, before returning to a subsequentengagemen with the primary blade assembly P1.

As previously stated, the division of one of the rotors, such as thesecondary rotor S, into multiple stages enables the blades of each stageS1 and S: to be given the most suitable form for the attainment of thehighest efficiency in view of the condition of the working fluid in theblade channels thereof. Consequently, the retardation of the workingfluid as it passes through the blade channels is effectively prevented,and acceleratiorr is imparted thereto which prevents the losses ineiilciency occurring in previously known torque converters lacking thisprovision, and permitting this retardation of the working fluid. If oneof the blade assemblies S1 or S: is given opposite characteristics fromthe other, as previously explained, such as when one is caused to exerta pump action and the other a turbine action, the operatingcharacteristics andtion, the provision of multiple stages on one or onboth of the rotors and the consequent adaptation of the blade assembliesand their cross sections or profiles to the speed and forcecharacteristics of the working fluid existing in the blade channelsbetween the blades, can be most efliciently correlated to the end thatthe torque converter operates most efiiciently under greatly varyingconditions of operation.

Referring now to Figure 8, the structure shown therein illustrates atorque converter with two primary blade assemblies and one secondaryblade assembly. The primary rotor P comprises a pump blade assembly P1,or [-2, and also a turbine blade assembly P3, or 5-6, whereas thesecondary rotor comprises the turbine blade assembly S1, or 3-4. Theguide wheel assembly is designated L, or 1-8, and may be held stationaryby any convenient means. As to the remaining elements of Figure 8, thesecorrespond to the elements of Figure 3 carrying the same referencecharacters as in Figure 8.

The profiles of the blade assemblies [-2, 34, 5-6, and 1--8 of Figure 8as well as the velocity diagrams pertaining thereto are illustrated inFigures 9, 10, 11 and 12 in a manner similar to that described above inconnection with Figures 3 to 7. The device of Figure 8 operatessimilarly as the structure of Figure 3 and will be understood withoutfurther description.

Figure 13, illustrating a further embodiment of this invention, shows atorque converter with two primary and two secondary blade assemblies.The primary rotor P comprises a pump blade assembly P1, or l-Z, and alsoa turbine blade assembly P3, or 5- 5, whereas the secondary rotorcomprises a. turbine blade assembly S1, or 34, and a pump blade assemblyS2, 0r'1.8. The guide wheel assembly is designated L, or 9-10, and maybe held stationary by any convenient means. Otherwise, the structure ofFigure 13 comprises similar to the device of Figure 8. a driving shaftW1, a driven shaft W: and ball bearings B1 and B2 for supporting thecasing which surrounds the blade assemblies P1 and Pa and is connectedto the shaft W2.

The blade assemblies I--2, 3-4, 5--6, 1-8, and 9|0, have their profilesshown in Figures 14, 15, 16, 17 and 18 respectively. These figures alsoshow the velocity diagrams pertaining to these profiles in a mannersimilar to that described in connection with Figures 3 to 7.

It is, of course, understood that the present invention is not limitedto the particular structure shown in the drawings but also embraces anymodifications within the scope of the appended claims.

Having thus fully described my invention. what Patent, is:

1. In a fluid power transmitter, a first rotor, a second rotor, each ofsaid rotors having rigidly connected thereto a pressure head generatingblade assembly, and at least one of said rotors having also rigidlyconnected thereto a pressure head consuming blade assembly, and a guideblade assembly interposed between two adjacent blade assemblies forguiding the fluid therebetween.

2. In a fluid power transmitter, a primary rotor having a pumping bladeassembly, a secondary rotor having a pumping blade assembly and aturbine blade assembly, and a guide blade as sembly interposed betweensaid pumping blade assembly and said turbine blade assembly of saidsecondary rotor.

3. In a fluid power transmitter, a primary rotor having rigidlyconnected thereto a turbine blade assembly and a pumping blade assembly,a guide blade assembly interposed between said pumping blade assemblyand said turbine blade assembly, and a secondary rotor having a turbineblade assembly.

4. A fluid power transmitter comprising in combination a primary rotor,at secondary rotor hydraulically connected with said primary rotor, eachof said rotors having rigidly connected thereto a pumping blade assemblyand one of said rotors having also rigidly connected thereto a turbineblade assembly, and a guide blade assembly arranged between two bladeassemblies of the same rotor for guiding the fluid therebetween.

5. In a torque converter, a rotatable casing, a brake engageable withsaid casing to selectively halt the rotation of said casing, a primaryrotor and a secondary rotor, both rotors being arranged within androtatable relative to said casing, each of said rotors having rigidlyconnected thereto a plurality of blade assemblies including a pumpingblade assembly and a turbine blade assembly, and a guide blade assemblysecured to said casing and arranged between two adjacent bladeassemblies not pertaining to one and the same rotor.

6. A torque converter, comprising in combination a rotatable casing, abrake engageable with said casing to selectively halt rotation of saidcasing, a first rotor and second rotor within said casing, said firstrotor having rigidly connected thereto at least one blade assembly andsaid second rotor having rigidly connected thereto a plurality of bladeassemblies including a pressure head generating blade assembly and apressure head consuming blade assembly, and a guide blade assemblysecured to said rotatable casing and disposed between two adjacent bladeassemblies.

7. In a fluid power transmitter, a primary rotor, a secondary rotor, atleast one of said rotors having rigidly connected therewith at least onepressure head generating blade assembly and at least one pressure headconsuming blade assembly, and a guide blade assembly, said bladeassemblies being arranged so that following the direction of flow offluid in said transmitter each blade assembly of one rotor is followedby one of the other blade assemblies not pertaining to guide bladeassembly generating blade assembly and a pressure head consuming bladeassembly, a secondary rotor having rigidly connected thereto a pressurehead consuming and a pressure head generating blade assembly, and aguide blade assembly arranged between two adjacent blade assemblies, oneor which pertains to one rotor, while the other pertains to the otherrotor.

9. In a fluid power transmitter, a primary rotor having a pressure headgenerating and a pressure head consuming blade assembly, a secondaryrotor having rigidly connected thereto a pressure head consuming and apressure head generating blade assembly, said blade assemblies beingarmrrz KUGEL.

